1. Field of the Invention
The present invention relates to a vacuum processing apparatus and vacuum processing methods typified by deposited film forming apparatus and deposited film forming methods using plasma enhanced CVD capable of forming on a substrate a deposited film. This invention relates more particularly to the formation of a functional deposited film, especially a non-monocrystalline semiconductor typified by amorphous semiconductors, an insulating coating such as silicon nitride, silicon carbide, or amorphous carbon, used in semiconductor devices, light-receiving members for electrophotography, line sensors for image input, image pickup devices, photovoltaic devices, and so on.
2. Related Background Art
Deposited films of semiconductors or the like made of amorphous materials such as amorphous silicon, for example, amorphous silicon compensated by hydrogen and/or halogen, have been proposed as element members for use in semiconductor devices, light-receiving members for electrophotography, line sensors for image input, image pickup devices, photovoltaic devices, other various electronics elements, and so on. Some of them are in practical use.
A variety of device forming apparatuses using amorphous silicon as described above have been proposed heretofore. For example, Japanese Patent Application Laid-open No. 58-83855 discloses a forming apparatus (of the coaxial type) for an amorphous silicon photosensitive member in which the cathode electrode and a cylindrical substrate are arranged on a coaxial basis. Further, Japanese Patent Application Laid-open No. 62-219524 discloses an example of a forming apparatus (of the concentric circle type) for an amorphous silicon photosensitive member with improved productivity, in which cylindrical substrates are arranged on one circle.
With recent improvements in overall performance of devices using amorphous silicon materials as described above, however, demands have increased for further improvement in the quality of the materials themselves, including various characteristics of amorphous silicon materials.
For example, in the field of electrophotography, there has been a strong push to save space and to lower prices in order to improve office environments.
On the other hand, demands have increased for further increase of copy image definition and for further increase of image formation speed. Under such circumstances demands for a decrease in the diameter of amorphous silicon photosensitive members and for commonality thereof have increased. At the same time, the tendency to specialize with respect to the diameters of photosensitive members also exists in order to make configurations optimum for characteristics of the electrophotographic process.
Under such circumstances, the conventional deposited film forming apparatus did not always meet the demands in some cases.
For example, in the case where an amorphous silicon photosensitive member for electrophotography was formed by the deposited film forming apparatus of the coaxial type as described above, changing the diameter of the photosensitive member also changed the diameter of a support member. It also resulted in changing the distance to the cathode and the like. This changed forming conditions of the deposited film, and in order to deal with the change, the apparatus needed to be modified, including the diameter of the cathode, change of evacuation position, and so on. Such modification normally required a period of several days.
In the case of the deposited film forming apparatus of the concentric circle type as described above, changing the diameter of the photosensitive member required changing the placement of substrates in order to form the discharge space. The modification usually required several days, too.
The dead time for the apparatus during modification caused degradation of operation rates of the starting material gas supply means and the evacuation system, thereby requiring big investments and other incidental facilities.
If photosensitive members of different diameters are intended to be produced by changing other deposition conditions without modifying the deposited film forming apparatus in order to avoid dead time, the apparatus configuration would deviate from the optimum shape. This would inevitably result in the occurrence of dispersion in the characteristics of the deposited film and the like or often requiring still more improvements for fully meeting recent, high desired performance demands.
The above problems occur not only in the case of formation of a deposited film, but also in the case of plasma processing of a surface to be processed. In such a case, it is considered important to optimize the configuration of the overall apparatus and its characteristics, due to variations in etch amount, modification amount, etc., though these variations are not as prominent as in the formation of deposited film.
An object of the present invention is, therefore, to provide a vacuum processing apparatus and vacuum processing method, typified by the deposited film forming apparatus and deposited film forming method, capable of efficiently, cheaply, and stably supplying non-monocrystalline semiconductor devices including high-quality amorphous silicon devices meeting the above demands and solving the above problems.
Another object of the present invention is to provide a vacuum processing apparatus and vacuum processing method capable of supplying non-monocrystalline semiconductor devices while suppressing dispersion of characteristics, by facilitating supply of desired gas such as starting material gas into a movable vacuum vessel, thus preventing the occurrence of leakage or the like, and stabilizing the supply of gas.
An object of the present invention is to provide a vacuum processing apparatus comprising a vacuum vessel capable of providing a substrate therein, the vacuum processing apparatus being arranged to evacuate the inside of the vacuum vessel by evacuation means, introduce a gas from gas supply means into the vacuum vessel, and apply high-frequency power from a high-frequency power source to electrodes, thereby generating a plasma, wherein the evacuation means comprises at least two evacuation means as first evacuation means and second evacuation means, wherein the vacuum vessel is moved between the two evacuation means while maintaining vacuum, and wherein the vacuum processing apparatus comprises a connection mechanism capable of detachably connecting the vacuum vessel to each of the evacuation means, high-frequency power source, and gas supply means.
Another object of the present invention is to provide the vacuum processing apparatus wherein the first evacuation means can be used as evacuation means for evacuating the vacuum vessel from atmospheric pressure to a vacuum and the second evacuation means can be used as evacuation means for evacuating the inside of the vacuum vessel during generation of the plasma.
A further object of the present invention is to provide the vacuum processing apparatus wherein in a connection part between the vacuum vessel and gas supply means, the connection mechanism has a double structure of a starting material gas supply pipe through which a starting material gas flows and an external pipe for separating a connection portion of the pipe for supply of starting material gas from the atmosphere and permitting evacuation to a vacuum. If necessary, this external pipe is constructed as a pipe for detachably connecting the vacuum vessel to the evacuation means.
Still another object of the present invention is to provide the vacuum processing apparatus wherein the connection portion of the gas supply pipe comprises valves capable of sealing the connection portion before and after the connection portion and a pressure gauge for measuring a pressure inside the gas supply pipe between the valves.
A further object of the present invention is to provide a vacuum processing method for evacuating the inside of a vacuum vessel provided with a substrate therein by evacuation means, introducing a gas into the vacuum vessel and applying high-frequency power thereto, thereby generating a plasma inside the vacuum vessel, wherein the evacuation means comprises at least two evacuation means as first evacuation means and second evacuation means, the vacuum processing method comprising the steps of: connecting the vacuum vessel to the first evacuation means to evacuate the vacuum vessel from atmospheric pressure to a vacuum, disengaging and moving the vacuum vessel from the first evacuation means while maintaining vacuum, connecting the vacuum vessel with each of gas supply means, the second evacuation means for evacuating the inside of the vacuum vessel, and a high-frequency power source, supplying energy from the power source to generate the plasma, and disconnecting the vacuum vessel from the second evacuation means, the gas supply means, and the high-frequency power source.
Another object of the present invention is to provide the vacuum processing method further comprising a step of, in connecting the vacuum vessel with the gas supply means, replacing the atmosphere inside of a gas supply pipe through which a gas flows with an inert gas, and thereafter measuring a seal pressure of a connection portion.
Another object of the present invention is to provide the vacuum processing method capable of, during generation of the plasma with the vacuum vessel being connected to the second evacuation means, gas supply means, and high-frequency power source, connecting another vacuum vessel to the first evacuation means and setting a substrate in or evacuating the other vacuum vessel.
In the vacuum processing apparatus of the present invention, achieving the above objects, the evacuation means is fixed, and the vacuum vessel is freely movable. Therefore, for example, when vacuum vessels preliminarily prepared to be suitable for the production of desired amorphous silicon devices are used, no modification is necessitated for the vacuum processing apparatus (deposited film forming apparatus in the case of formation of deposited film) even for the production of many kinds and small numbers of lots. In this way, the dead time of the producing apparatus can be minimized. Since optimum configurations can be selected for respective vacuum vessels suitable for production methods of respective individual amorphous silicon devices, high-quality devices can be provided on a stable basis.
Further, since the vacuum vessel is movable, when a plurality of vacuum vessels are used, one vacuum vessel can be subjected to maintenance at a position apart from the evacuation means, while formation of a deposited film can be carried out in another vacuum vessel.
Accordingly, the dead time of a deposited film forming apparatus can also be minimized from this point, and high-quality devices can be supplied at low prices.
The present invention is effective not only in the formation of deposited film, but also in applications to plasma processing such as etching or modification of a processed body by use of plasma (for example, compensation for dangling bonds by hydrogen plasma). However, when the present invention is applied to the formation of a deposited film, its most prominent effect is seen in the fabrication of devices of higher performance and higher quality. Thus, the application to the formation of a deposited film is a preferred application. Particularly, a preferred application is the fabrication of devices having a non-monocrystalline material such as amorphous silicon, especially fabrication of optical devices typified by the photosensitive members for electrophotography.